\ba Unicode word boundary
\d+a Unicode decimal digit, repeated at least once
\.the literal . (4610 / 568 / 2E16)
txtthe literal text txt (case sensitive) \ba Unicode word boundary
g modifier: global. Finds all matches instead of stopping after the first
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string